Measurement strategies for the determination of airborne bacterial endotoxin in sewage treatment plants.

Working in sewage plants can involve exposure to different types of microorganisms, viruses and chemicals. The purpose of this study was to evaluate different measurement strategies to determine airborne bacterial endotoxin in such plants. Sewage treatment plants in three municipalities in western Sweden were included. Measurements of airborne endotoxin were performed in April-May and September-October 2001 using personal and stationary samplers. The air sampling times ranged from 60 to 444 min. In stationary and personal sampler measurements, the amounts of airborne endotoxin detected were generally low. At specific worksites, however, higher endotoxin values were identified, with the highest values at worksites located indoors. The results suggest that the exposure situation is relatively stable over a short time period at a specific worksite and that higher values can be recorded during work practices where agitation of wastewater occurs. The results further suggest that airborne endotoxin exposure situations in sewage treatment plants are complex. Sampling techniques, indoor/outdoor measurements and identification of specific worksites/tasks where there is a risk of airborne endotoxin exposure are important factors that must be considered in order to obtain relevant exposure determinations and establish preventive measures from a health risk perspective.